Rock drill bit



March 2.4, 1953 BAKER I 2,632,662

ROCK DRILL BIT Filed March 8, 1950 g INVENTOR.

JOHN B. BAKER,

2%? am VM,

Patented Mar. 24, 1953 ROCK DRILL BIT John B. Baker, Canton, Ohio, assignor to The 'Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio Application March 8, 1950, Serial No. 148,488

3 Claims.

This invention relates to rock drill bits and is more particularly directed to bits that can be easily replaced after their period of usefulness has been exhausted.

The object of the invention is to provide a replaceable rock drill bit for a'drill rod that can be inserted into the socket of the bit, the latter being held on the rod by frictional contact without fatiguing or spalling the drill rod.

The invention consists in the provision of a drill bit provided with a cylindrical sectioned socket, the base of which is provided with a hardened annular ridge whose apex is directed toward the open end of the socket in which a comparatively soft drill rod is inserted. The ridge is imbedded in the drill rod by the load imposed on the drill bit.

In the drawings:

Fig. 1 is an end view of the drill bit,

Fig. 2 is a sectional view taken along the line 22 of Fig. 1; and

Fig. 3 is a view of the assembled drill bit with parts in section to show detail.

This invention is embodied in the several views of the drawings in which the numeral l designates the drill bit body provided with radial cutting edges 2 on on end thereof. The other end of the body is provided with a circular sectioned socket 3 having a fiat bottom or base 4.

p A triangular ridge 5 is formed on the base of V the socket, the included angle between the sides of the projecting portion of the ridge preferably being 60, the ridge pointing toward the open end of the socket. The entire body, including the ridge, is hardened.

An unhardened cylindrical drill rod 6 is inserted in the socket 3. The drill rod snugly fits the socket and when a drill load is applied to the bit body, the ridge is imbedded in the end of the drill rod, the ridge being disposed radially inwardly from the walls of the socket. Therefore the ridge can be imbedded in the drill rod,

thus spreading the end of the rod so that the frictional engagement between the rod and the body member is thereby increased.

Ina bit constructed as described, the metal at the end of the drill rod is only displaced enough to maintain a frictional contact with the bit body. The end of the drill rod is not unduly stressed by being forced from its normal position. When removing the bit, only the friction need be overcome and no moving of the metal occurs. There is no weakening grooves or cavities in the wall of the bit. Replacing worn bits is very easily accomplished by tapping thereon with a hammer. The end of the drill rod will last "longer before redressing because it is stressed less. When redressing is required, it is slight, it being only necessary to make the groove shallow enough to make the upsetting during use, maintain frictional engagement with the bit. The drill rod will not fatigue and spall, as occurs in prior art devices, is eliminated or greatly reduced.

The ridge 3 is shown as continuous but may be interrupted or broken into a number of segments. The specification describes a rod of round section cooperating with the round socket and ridge, but a difierently shaped socket and rod, such as a square, hexagonal or any other sectioned drill rod may be employed when a similarly sectioned socket is formed in the drill bit.

What I claim is:

1. A rock drill bit comprising a body provided with a socket having uninterrupted side walls, an annular hardened ridge on the bottom wall of said socket disposed inwardly from the sides thereof and pointing toward the open end of said socket; and a drill rod received in said socket that is softer than the ridge, the ridge imbedding itself in the drill rod by the load applied to the drill bit body.

2. A rock drill bit comprising a drill bit body member provided with a circular flat-bottomed socket having uninterrupted side walls, a hardened annular triangular ridge formed on said bottom disposed inwardly from the sides of the socket whose apex is pointed toward the open end of said socket, a cylindrical drill rod that is softer than the triangular ridge inserted in said socket and frictionally held therein by said ridge which is imbedded in the end thereof by the load applied to the drill bit.

3. A rock drill bit comprising a hardened body member provided with a fiat-bottomed circular socket having uninterrupted side walls, an annular hardened triangular ridge on said socket base whose apex is pointed toward the open end of said socket and which is spaced radially inwardly from the socket wall, a drill rod softer than said drill bit and ridge disposed in said socket, said rod frictionally held in said socket by reason of said ridge being imbedded in said drill rod when a load is applied to said drill bit.

JOHN B. BAKER.

REFERENCES CITED The following references are of record in the 'Name Date Liddicoat Mar. 4, 1941 Number 

